Pancreatic ductal adenocarcinoma is a relatively uncommon cancer with an almost universally fatal outcome. Chronic pancreatitis (CP) is a risk factor for pancreatic ductal adenocarcinoma (PDA), presumably due to the pro-tumorigenic effects of the inflammatory microenvironment. Besides inflammation, the two diseases have many common features, including ductal metaplasia and fibrosis, both of which may significantly enhance PDA formation. We have found that genetic ablation of the cell surface metalloproteinase ADAM17 specifically from the pancreas makes mice highly resistant to both CP and PDA, thus representing a precise molecular link between these diseases. The purpose of the current proposal is to dissect the mechanisms and define the ADAM17 substrates that contribute to pancreatic disease progression. In Aim 1 we will use genetic ablation and pharmacological inhibition of ADAM17 substrate-dependent pathways to determine which substrates influence both acinar-to-ductal transdifferentiation and inflammatory cell chemotaxis, in vitro. In Aim 2, we will use genetic ablation and pharmacological inhibition of the epidermal growth factor receptor (EGFR) and its family member ERRBB3 to test if EGFR ligands released by ADAM17 are responsible for its effects on CP and PDA using in vivo mouse models. In Aim 3, we will use pharmacological inhibition of ADAM17 released cytokines tumor necrosis factor alpha (TNFa) and interleukin 6 receptor (IL6R) to test for their influence on the etiology of pancreatic inflammation and PDA in vivo.